Sample Midterm

These are sample questions that are very similar to the ones I will ask on the midterm.

1. Which of the following is not a valid C variable name?
   1. hello
   2. chomp_burp
   3. whilex
   4. more-more-more
   5. TrUcKiNg
2. Evaluate the following expressions, assuming a = 1, b = -3, and c = 0. Treat them independently, so (for example) after evaluating (b), use the above values for (c).
   1. a + b < c
   2. c == !a == c
   3. a = ++b; give the values of both a and b as well
   4. a-- == !b; give the value of a as well
   5. a / b
3. True or False: If x = -1, then if (x) printf("1"); else printf("2"); prints 2.
4. Write a recursive function to add the integers from a to b. Please assume that a ≤ b.
5. What are all possible outputs of the following code fragment?

   void f(int a, int b)
   {
       printf("%d %d\n", a, b);
   }
   
   void main(void)
   {
       int i = 5;
       f(i++, i++);
   }
   

6. Given the definitions

       int numbs[10];
       int *ptr = numbs;
   

   which of the following are equivalent, and why?
   1. numbs[3]
   2. numbs + 3
   3. *(numbs + 3)
   4. *(ptr + 3)
   5. *ptr + 3
7. Use the following code fragment to answer parts (a), (b), and (c):

   for(x = i = 0; i <= 100; i += 2, x += i);
   

   1. In one short sentence, what does this for loop do?
      
   2. Is the following while loop equivalent? If not, how does its result differ? (Hint: look at the values of both x and i.)

          x = i = 0;
          while( i++ <= 100)
              x += ++i;
      

   3. Does the following for loop do the same thing? If not, what does it do?

          for(x = i = 0; i <= 100; i++){
              if (!(i % 2))
                  continue;
              x = x + i;
      }
      

8. What does this function do?

   char *x(char *s, char c)
   {
       char *r = NULL;
   
       do{
           while(*s && *s != c)
               s++;
           if (*s)
               r = s; 
       } while(*s++);
       return(r);
   }
   

9. The following segment of code is supposed to print the number of times the routine a_again is called. Yet, regardless of the input, it prints 0. Why? How would you fix it?

   void a_again(int acount)
   {
       ++acount;
   }
   
   int main(void)
   {
       int c;
       int counter = 0;
   
       while((c = getchar()) != EOF)
           if (c == 'a' || c == 'A')
               a_again(counter);
   
       printf("%d\n", counter);
       return(0);
   }
   

Matt Bishop Office: 2209 Watershed Sciences Phone: +1 (530) 752-8060 Email: [email protected]

ECS 36A, Programming and Problem Solving Version of October 21, 2019 at 6:32PM

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